The present invention relates generally to transmission of radiant energy and more particularly to devices which may be constructed to collect radiant energy from within a field of selected angular characteristics or alternatively to emit radiant energy throughout a field of selected angular characteristics or both. As such, the invention relates to radiant energy concentrative and emissive functions and combinations thereof useful for such purposes as energy display, energy transformation and coupling other energy transmission devices. Devices according to the present invention include radiant energy reflecting and guiding walls developed at the interface of media of differing indices of refraction for radiant energy and optimally operative to substantially provide total internal reflection of such radiant energy.
The prior art has proposed and includes numerous structures and devices for electromagnetic or radiant energy detection, collection, concentration, transmission, transformation, propagation and emission of widely differing forms, including those naturally occurring [e.g., photosensitive "optical" elements in animals as described in J. Opt. Soc. Am., Vol. 61, No. 8, pp. 1120-21 (1971)]; image-forming lenses, fibers and the like; reflective layers and coatings for focusing and scattering; as well as uncoated transparent fibers, light pipes and the like.
Quite frequently devices and systems useful in one mode of energy transmission have for the most part been ineffective or inefficient when operation in an alternative mode has been attempted. Further, technological advances in certain fields of radiant energy transmission have not been matched in advances in necessarily complementary fields. Examples for this state of events are abundant. Photoelectric cells have been produced which have a capacity for converting radiant energy into electrical energy beyond the ordinary capacity of transmission devices to supply operative surfaces of such cells with radiant energy in a manner to make the "trade-off" involved in the energy conversion economically feasible. Similarly, use of reflective (e.g., silvered) layers and mirrored surfaces to focus and/or scatter radiant energy quite often fail in applications involving multiple reflections wherein the relatively "minor" absorptive characteristics of such layers and surfaces are a significant deterent to efficient transmission. As another example, imaging systems such as lenses and the like which are generally quite efficient in transmitting energy eminating from a fixed source, require a "trade-off" in terms of tracking when the energy source is transient and/or diffused. Energy transmission systems of an internally reflective variety such as light fibers and light pipes quite adequately function in transmission of rays of certain angular origin but may be quite inefficient and "leak" when called into operation for transmission of energy of differing angularity.
Recent proposals for the use of "ideal" radiant energy reflective surfaces developed in substantially trough-like and conical configurations have met with substantial success, especially in applications involving collection and concentration of solar energy. Thus, for example, my U.S. Pat. No. 3,923,381 discloses, inter alia, non-imaging radiant energy collecting and concentrating devices generally including opposed reflective surfaces sloped to reflect the maximum angle energy rays within the device's field of acceptance on an energy trap--allowing concentration by substantial factors, avoidance of transient energy source tracking and general minimization of absorptive losses due to multiple reflections. In a similar manner, U.S. Pat. No. 3,899,672 of Levi-Setti discloses, inter alia, non-imaging conically-shaped energy collectors and concentrators having similarly advantageous energy transmission characteristics. Complimentary disclosures relative to this subject matter are contained in my publications, "Principles Of Solar Concentrators Of A Novel Design," Solar Energy, Vol. 16, pp. 89-95 (1974) and Solar Energy Concentrations, Progress Report NSF/RANN AER 75-01065 (February, 1975), the latter of which specifically relates to principles for maximally concentrating radiant energy onto a tube receiver through use of cylindrical trough-like reflecting wall light channels of specific shape which concentrate radiant energy by the maximum amount allowed by phase space conservation.
To the extent that my said U.S. Pat. Nos. 3,923,381, 3,899,672, my recent publications, "Principles Of Solar Concentrators Of A Novel Design, " Solar Energy, Vol. 16, pp. 89-95 (1974) and Solar Energy Concentration, Progress Reports NSF/RANN AER 75-01065 (February and July, 1975) contain "essential material" necessary to support the claims hereof or provide statutorily adequate disclosure or "non-essential subject matter" indicating the background of the invention and/or illustrating the state of the art, the disclosures thereof are expressly incorporated by reference herein.
Also specifically incorporated by reference herein for purposes of indicating the background of the invention and/or the state of the art are the following patents and publications: Tabor, Solar Energy, Vol. II, No. 3-4, pp. 27 et seq. (1958); Sleeper, U.S. Pat. No. 3,125,091; Meinel et al., Physics Today, Vol. 25, pp. 684 et seq. (1972); Falbel, U.S. Pat. No. 3,179,105; Hintenberger and Winston, Rev. Scientific Instruments, Vol. 37, No. 8, pp. 1094-95 (1966); Hintenberger and Winston, Rev. Scientific Instruments, Vol. 39, No. 8, pp. 1217-18 (1968); Winston, J. Opt. Soc. Am., Vol. 60, No. 2, pp. 245-47 (1070); Winston, J. Opt. Soc. Am., Vol. 61, No. 8, pp. 1120-21 (1971); Williamson, J. Opt. Soc. Am., Vol. 42, No. 10, pp. 712-15 (1952); Witte, Infrared Physics, Vol. 5, pp. 179-85 (1965); Emmett, U.S. Pat. No. 980,505; Baranov, et al., Soviet Journal of Optical Technology, Vol. 33, No. 5, pp. 408-11 (1966); Baranov, Soviet Journal of Optical Technology, Vol. 34, No. 1, pp. 67-70 (1967); Baranov, Applied Solar Energy, Vol. 2, No. 3, pp. 9-12 (1968); Newton, U.S. Pat. No. 2,969,788; Phillips, et al., U.S. Pat. No. 2,971,083; Florence, U.S. Pat. No. 3,591,798; U.S.S.R. Certificate of Authorship No. 167,327 to V. K. Baranov, published on Jan. 4 and Mar. 18, 1965; U.S.S.R. Certificate of Authorship No. 200,530 to V. K. Baranov, published on Aug. 15 and Oct. 31, 1967; Perlmutter, et al., U.S. Pat. No. 3,229,682; Perlmutter, et al., Journal of Heat Transfer, August, 1963, pp. 282-83; Winston, et al., Solar Energy, Vol. 17, No. 4, pp. 255-58 (1975).